From: Dan Harris <fbsd@drivefaster.net>
To: pgsql-performance <pgsql-performance@postgresql.org>
Subject: Re: Slow count(*) again...
Date: Tue, 12 Oct 2010 09:39:19 -0600
Message-ID: <4CB48127.6090200@drivefaster.net> (raw)
In-Reply-To: <90E30938-1E5E-4DCA-A1FB-AEECEB76A70D@richrelevance.com>
References: <201010091626.18636.neil.whelchel@gmail.com>
<4CB11CC7.8070300@vmsinfo.com>
<4CB167CA.9070109@postnewspapers.com.au>
<4CB1F46E.80205@vmsinfo.com>
<90E30938-1E5E-4DCA-A1FB-AEECEB76A70D@richrelevance.com>
On 10/11/10 8:02 PM, Scott Carey wrote:
> would give you a 1MB read-ahead. Also, consider XFS and its built-in defragmentation. I have found that a longer lived postgres DB will get extreme
> file fragmentation over time and sequential scans end up mostly random. On-line file defrag helps tremendously.
>
We just had a corrupt table caused by an XFS online defrag. I'm scared
to use this again while the db is live. Has anyone else found this to
be safe? But, I can vouch for the fragmentation issue, it happens very
quickly in our system.
-Dan
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To: pgsql-performance@postgresql.org
Cc: fbsd@drivefaster.net
Subject: Re: Slow count(*) again...
In-Reply-To: <4CB48127.6090200@drivefaster.net>
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